1. Technical Field
The inventive concept relates to a nonvolatile memory device, and more particularly, to a phase-change random access memory (PRAM) device and a method of manufacturing the same.
2. Related Art
In recent years, as semiconductor memory devices, next-generation devices that are nonvolatile and are not necessary refresh have been researched with demands on high performance and low power. The next-generation memory devices may include PRAMs.
The PRAMs have properties that a resistance value thereof may be changed according to current or voltage and maintained as it is when the current or voltage is interrupted.
The PRAMs perform a memory operation by receiving current from a lower electrode and heating a phase-change material to change a resistance value. For example, when a reset pulse is applied to the phase-change material, the phase-change material is melted to be in a high resistance state, for example, logic value “1”, and when a set pulse is applied to the phase-change material, the phase-change material is in a low resistance state, for example, logic value “0”.
However, a heating temperature of the phase-change material constituting the PRAMs is proportional to an amount of current and thus it may be difficult to obtain high degree of integration. In particular, since current required for switching to the reset state larger than that required for switching to the set state, it may be desirable to reduce the current for the switching to the reset state in order to obtain high degree of integration.